Pandas only writes the last 4 entries...

import serial
import pandas as pd

serPort = serial.Serial("/dev/ttyUSB0")

print(serPort.name)

while True:
    dataRaw = serPort.readline().strip()
    dataList = dataRaw.decode('ascii').split(', ')
    data = [int(d) for d in dataList]

    print(data)

    df = pd.DataFrame(data)
    df.to_csv('data.csv', sep=',', index=False)

serPort.close()